Understanding 'Liminal' in Context

In the realm of literature, characters often exist in the liminal spaces between morality and immorality. The protagonist of our story grapples with his decisions, oscillating between righteous indignation and dubious justifications for his actions. While he perceives his quest as virtuous, the subtle nuances of his behavior suggest a descent into moral ambiguity. In this context, the passage delves into the complexities of human nature, illustrating how individuals can become ensnared by their own ideals while distancing themselves from the ethical standards they once upheld.

The term 'liminal' in this passage is best understood as: